U.S. patent number 5,303,337 [Application Number 07/659,718] was granted by the patent office on 1994-04-12 for method and device for determining a viewing perspective for image production.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Tomotoshi Ishida.
United States Patent |
5,303,337 |
Ishida |
April 12, 1994 |
Method and device for determining a viewing perspective for image
production
Abstract
An image display method and an image display system in which,
based on a relative positional relationship between a
three-dimensional image displayed on an image screen and an
optional position designated by an operator on said image screen,
the three-dimensional image is displayed after being rotated by a
predetermined angle with respect to the relative positional
relationship. An image is obtained by rotating the
three-dimensional image by 90 degrees around a line which is
orthogonal to a line connecting a center position of the
three-dimensional image displayed on the image screen with the
optional point designated by the operator on the image screen,
thereby making it possible to designate a display perspective of a
design object with operating sense which conforms with the design
intent of the designer.
Inventors: |
Ishida; Tomotoshi (Katsuta,
JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
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Family
ID: |
12722822 |
Appl.
No.: |
07/659,718 |
Filed: |
February 25, 1991 |
Foreign Application Priority Data
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Feb 28, 1990 [JP] |
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2-045563 |
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Current U.S.
Class: |
345/419; 345/427;
715/849 |
Current CPC
Class: |
G06T
19/20 (20130101); G06T 2219/2016 (20130101); G06T
2219/028 (20130101) |
Current International
Class: |
G06T
17/40 (20060101); G06F 015/72 (); G06F
015/60 () |
Field of
Search: |
;395/119,127,137,161,157
;340/729 ;364/474.24,474.22 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0451875 |
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Oct 1991 |
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EP |
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2634922 |
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Feb 1990 |
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FR |
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46565 |
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Mar 1986 |
|
JP |
|
305475 |
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Dec 1989 |
|
JP |
|
Other References
"HITAC Program Product GRADAS Three-Dimensional Design System
HICAD/3D Principles of Operation" (8090-7-034-40), 1988, pp. 150,
154, 155 (Japanese Language Literature)..
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Primary Examiner: Bayerl; Raymond J.
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus
Claims
I claim:
1. For projecting and displaying a three-dimensional model
representing a shape of a three-dimensional object on a
two-dimensional image screen, a method of determining a viewing
perspective for image production comprising the steps of:
projecting said three-dimensional model, based on a first
predetermined viewing perspective to generate a first projected
image;
displaying said first projected image at a predetermined position
on said screen;
designating an arbitrary position on said screen by an
operator;
generating information of a relative positional relationship
between the display position of said first projected image on said
screen and said designated arbitrary position;
computing a second viewing perspective which is formed when said
first viewing perspective is rotated by a predetermined angle,
based on said information of the relative positional
relationship;
projecting said three-dimensional model based on said second
viewing perspective to generate a second projected image; and
displaying said generated second projected image at said designated
position on said screen.
2. For projecting and displaying a three-dimensional model
representing a shape of a three-dimensional object on a
two-dimensional image screen, a method of determining a viewing
perspective for image production comprising the steps of:
projecting said three-dimensional model on a projection plane,
based on a first predetermined viewing perspective to generate a
first projected image;
displaying said first projected image at a predetermined position
on said screen;
designating an arbitrary position on said screen by an
operator;
computing a rotating direction perpendicular to a line connecting
the display position of said first projected image on said screen
and said designated arbitrary position to compute a rotating
direction on said projection plane in a three-dimensional space
which corresponds to said computed rotating direction on the
screen;
computing a second viewing perspective which is formed when said
first viewing perspective is rotated by 90 degrees in said computed
rotating direction;
projecting said three-dimensional model, based on said second
viewing perspective to generate a second projected image; and
displaying said generated second projected image at said designated
arbitrary position on said screen.
3. For projecting and displaying a three-dimensional model
representing a shape of a three-dimensional object on a
two-dimensional image screen, a method of determining a viewing
perspective for image production comprising the steps of:
projecting said three-dimensional model on a projection plane,
based on a first predetermined viewing perspective to generate a
first projected image;
displaying said first projected image at a predetermined position
on said screen;
designating one line constructing said first projected image on
said screen by an operator;
designating an arbitrary position on said screen by an
operator;
computing a rotating direction of said designated line, a rotating
direction of a tangential line with respect to said designated line
or a rotating direction perpendicular to said designated line to
compute a rotating direction of said projection plane in a
three-dimensional space which corresponds to said computed rotating
direction on the screen;
computing a second viewing perspective which is formed when said
first viewing perspective is rotated by 90 degrees in said computed
rotating direction
projecting said three-dimensional model, based on said second
viewing perspective to generate a second projected image; and
displaying said generated second projected image at said designated
arbitrary position on said screen.
4. For projecting and displaying a three-dimensional model
representing a shape of a three-dimensional object on a
two-dimensional image screen, a method of determining a viewing
perspective for image production comprising the steps of:
projecting said three-dimensional model on a projection plane,
based on a first predetermined viewing perspective to generate a
first projected image;
displaying said first projected image at a predetermined position
on said screen;
designating one cutting line constructing said first projected
image on said screen by an operator;
designating an arbitrary position on said screen by an
operator;
computing a rotating direction of a projection plane in a
three-dimensional space which corresponds to a direction of said
cutting line;
computing a second viewing perspective which is formed when said
first viewing perspective is rotated by 90 degrees in said computed
rotating direction;
generating a cutting plane in which a line having the computed
rotated direction is extended perpendicularly to said projection
plane;
projecting said cutting plane in said three-dimensional model,
based on said second viewing perspective to generate a second
projected image; and
displaying said generated second projected image at said designated
arbitrary position on said screen.
5. For projecting and displaying a three-dimensional model
representing a shape of a three-dimensional object on a
two-dimensional image screen, a method of determining a viewing
perspective for image production comprising the steps of:
projecting said three-dimensional model, based on a first
predetermined viewing perspective to generate a first projected
image;
displaying said first projected image at a predetermined position
on said screen;
designating an arbitrary position on said screen by an
operator;
computing a rotating direction perpendicular to a line connecting
the display position of said first projected image on said screen
and said designated position to apply a predetermined rotation
processing to said computed rotating direction and to compute
another rotating direction on the projection plane in a
three-dimensional space which corresponds to said computed rotating
direction on the screen subjected to the rotation processing;
computing a second viewing perspective which is formed when said
first viewing perspective is rotated by 90 degrees in said computed
rotating direction;
projecting said three-dimensional model, based on said second
viewing perspective to generate a second projected image; and
displaying said generated second projected image at said designated
arbitrary position on said screen.
6. In a system for projecting and displaying a three-dimensional
model representing a shape of a three-dimensional object on a
two-dimensional image screen, a device for determining a viewing
perspective for image production comprising the steps of:
first projection means for projecting said three-dimensional model,
based on a first predetermined viewing perspective to generate a
first projected image;
first display means for displaying said first projected image at a
predetermined position on said screen;
position inputting means for inputting an arbitrary position on
said screen designated by an operator;
positional relationship generating means for generating information
of a relative positional relationship between the display position
of said first projected image on said screen and said designated
arbitrary position input by said position inputting means;
viewing perspective computing means for computing a second viewing
perspective which is formed when said first viewing perspective is
rotated by a predetermined angle, based on said information of the
relative positional relationship;
second projection means for projecting said three-dimensional
model, based on said second viewing perspective to generate a
second projected image; and
second display means for displaying said generated second projected
image at said arbitrary position on said screen input by said
position inputting means.
7. In a system for projecting and displaying a three-dimensional
model representing a shape of a three-dimensional object on a
two-dimensional image screen, a device for determining a viewing
perspective for image production comprising:
first projection means for projecting said three-dimensional model
on a projection plane, based on a first predetermined viewing
perspective to generate a first projected image;
first display means for displaying said first projected image at a
predetermined position on said screen;
a position inputting means for inputting an arbitrary position on
said screen designated by an operator;
rotating axis direction computing means for computing a rotating
direction perpendicular to a line connecting the display position
of said first projected image on said screen and said designated
arbitrary position input by said position inputting means to
compute a rotating direction on the projection plane in a
three-dimensional space which corresponds to said computed rotating
direction on the screen;
viewing perspective computing means for computing a second viewing
perspective which is formed when said first viewing perspective is
rotated by 90 degrees in said computed rotating direction computed
by said rotating axis direction computing means;
second projection means for projecting said three-dimensional
model, based on said second viewing perspective to generate a
second projected image; and
second display means for displaying said generated second projected
image at said designated arbitrary position on said screen input by
said position inputting means.
8. In a system for projecting and displaying a three-dimensional
model representing a shape of a three-dimensional object on a
two-dimensional image screen, a device for determining a viewing
perspective for image production comprising:
first projection means for projecting said three-dimensional model
on a projection plane, based on a first predetermined viewing
perspective to generate a first projected image;
first display means for displaying said first projected image at a
predetermined position on said screen;
line inputting means for inputting one line constructing said first
projected image which is designated by an operator;
position inputting means for inputting an arbitrary position on
said screen which is designated by an operator;
rotating axis direction computing means for computing a rotating
direction of said line input by said line inputting means, a
rotating direction of a tangential line with respect to said
designated line or a rotating direction perpendicular to said
designated line to compute a direction of the projection plane in a
three-dimensional space which corresponds to said computed rotating
direction on the screen;
viewing perspective computing means for computing a second viewing
perspective which is formed when said first viewing perspective is
rotated by 90 degrees in said computed rotating direction computed
by said rotating axis computing means;
second projection means for projecting said three-dimensional
model, based on said second viewing perspective to generate a
second projected image; and
second display means for displaying said generated second projected
image at said arbitrary position on said screen input by said
position inputting means.
9. In a system for projecting and displaying a three-dimensional
model representing a shape of a three-dimensional object on a
two-dimensional image screen, a device for determining a viewing
perspective for image production comprising:
first projection means for projecting said three-dimensional model
on a projection plane, based on a first predetermined viewing
perspective to generate a first projected image;
first display means for displaying said first projected image at a
predetermined position on said screen;
cutting line inputting means for inputting one cutting line
constructing said first projected image on said screen which is
designated by an operator;
position inputting means for inputting an arbitrary position on
said screen which is designated by an operator;
rotating axis direction computing means for computing a rotating
direction of a projection plane in a three-dimensional space which
corresponds to a rotating direction of said cutting line;
viewing perspective computing means for computing a second viewing
perspective which is formed when said first viewing perspective is
rotated by 90 degrees in said computed rotating direction computed
by said rotating axis direction computing means;
cutting plane generation means for generating a cutting plane in
which a line having the computed rotating direction computed by
said rotating axis direction computing means is extended
perpendicularly to the projection plane;
second projecting means for projecting said cutting plane in said
three-dimensional model, based on said second viewing perspective
to generate a second projected image; and
second display means for displaying said generated second projected
image at said arbitrary position on said screen input by said
position inputting means.
10. In a system for projecting and displaying a three-dimensional
model representing a shape of a three-dimensional object on a
two-dimensional image screen, a device for determining a viewing
perspective for image production comprising:
first projection means for projecting said three-dimensional model
on a projection plane, based on a first predetermined viewing
perspective to generate a first projected image;
first display means for displaying said first projected image at a
predetermined position on said screen;
position inputting means for inputting an arbitrary position on
said screen designated by an operator;
rotating axis direction computing means for computing a rotating
direction perpendicular to a line connecting the display position
of said first projected image on said screen and said position on
said screen input by said position inputting means to apply a
predetermined rotation processing to said computed rotating
direction and to compute a rotating direction on the projection
plane in a three-dimensional space which corresponds to said
rotating direction on the screen subjected to the rotation
processing;
viewing perspective computing means for computing a second viewing
perspective which is formed when said first viewing perspective is
rotated by 90 degrees in said computed rotating direction computed
by said rotating axis direction computing means;
second projection means for projecting said three-dimensional
model, based on said second viewing perspective to generate a
second projected image; and
second display means for displaying said generated second projected
image at said arbitrary position on said screen input by said
position inputting means.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an image display method and an
image display system in case of designing a three-dimensional
configuration and the like.
When a three-dimensional configuration is displayed with a CAD
system and so on, an operator judges the quality of the
configuration, watching the three-dimensional configuration from an
optional direction and performs a combining operation of various
configurations. This is for forecasting and judging workmanship of
an object to be designed or to design objects only by data
processing with a computer without actually producing the object,
and for producing configuration information of the object to be
designed. Further, in order to forecast in advance, when an
operation command is given to a machine tool, a robot and the like,
how they are operated and to what extent they interfere with other
members, it is required to observe raw materials, tools, parts,
arms and the like on a computer image plane.
When it has been desired to display a three-dimensional image on an
image screen from a certain other point of view, for example, when
a certain object being displayed is desired to be viewed from the
right side or from the left side, the viewing direction has been
heretofore designated as follows.
For example, in a most fundamental first prior art, the direction
is designated by numeric values. That is, a directional vector line
of sight and a vector in an upward direction on an image screen are
designated with numeric values and an angle of rotation from a
reference direction is designated with numeric values in an
ordinate system in a three-dimensional space.
In a second prior art, the viewing direction is selected by having
numerals correspond to several display directions which have been
prepared in advance (for example, "1" corresponds to the direction
viewed from the front, "2" corresponds to the direction viewed from
the right and so on), and designating the corresponding numeral to
a particular direction. That which is related to this second prior
art is described in a manual "HITAC Program Product GRADAS
Three-Dimensional Design System HICAD/3D Principles of Operations
(8090-7-034-40) p. 155 issued by Hitachi, Ltd.
In a third prior art, when a certain three-dimensional image has
already been displayed, rotating angles for further rotating the
three-dimensional image which is being displayed (angles viewed
from top and bottom, angles viewed from right and left, angles for
rotating clockwise and counterclockwise around an axis which is
perpendicular to the image screen and so on) are input from a dial
or a keyboard by designating numeric values. This prior art is also
described in page 150 of the manual of the second prior art.
In a fourth prior art, one straight line in a displayed
configuration is designated as an axis of rotation, and the image
is rotated around the axis by a rotating angle designated by one
dial.
In a fifth prior art, a display direction of a configuration which
is newly displayed is designated using several points, lines or
faces in a configuration which is being displayed. For example,
when two straight lines which are perpendicular to each other are
designated, the configuration is displayed so that the straight
line designated at the beginning becomes the horizontal direction
of the configuration which is newly displayed and the straight line
designated later becomes the vertical direction. (This prior art is
described on page 154 in above-mentioned manual, and will be
described later with reference to FIG. 17.) Further, when one face
and one straight line which is parallel to the face are designated,
the configuration is displayed so that the designated face is
parallel to the display screen and the designated straight line
shows a horizontal direction.
In a sixth prior art, when one sphere is displayed and one point on
the sphere is designated, a body is displayed with a vector
connecting the point and the center of the sphere to determine
direction.
As other prior arts reference, JP-A-1-305475 and JP-A-61-46565 may
be mentioned as being relevant.
According to the prior arts described above, it is possible to
display a three-dimensional image when a design object is viewed
from an optional direction. For example, in the above-described
fifth prior art, an operator designates a straight line 201 on a
right side surface and a straight line 202 on a bottom surface one
after another as seen on the design object shown in FIG. 17A which
are seen from various directions and are displayed on the image
screen. Accordingly, the design object is displayed so that the
straight line 201 lies in a horizontal direction and the straight
line 202 lies in a vertical direction on the left side of the image
screen as shown in FIG. 17B. Also, when the operator designates the
straight line 202 and the straight line 201 in successive order,
the display is made so that the straight line 202 lies in a
horizontal direction and the straight line 201 lies in a vertical
direction as shown in FIG. 17C. Furthermore, when the operator
designates a straight line 202 and a straight line 203, display is
made so that the straight line 202 lies in a horizontal direction
as shown in FIG. 17D.
It is possible for an operator to designate the display direction
of a design object optionally as described above, but questions
arise regarding accuracy and ease of the designating operation. In
respective prior arts described above, no consideration has been
given to ease of the designating operation, thus the operation
remains complex and inconvenient. For example, when it is desired
to look at the image shown in FIG. 17C, the operator has to
determine which two straight lines are to be designated in FIG. 17A
and how the designating order should be, by picturing in the
operator's brain, the displayed image in FIG. 17C in a
three-dimensional coordinate system to oneself in advance. With
such a method, the operator has to repeat trials and errors until
an objective image is obtained. The same applies to other prior
arts, and furthermore, only an image in a predetermined direction
can be seen and a display direction has to be designated with
numeric values, thus requiring operating sense which is different
from design intentions of the designer.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image
display method and an image display system which are capable of
designating a display perspective of a design object with operating
sense which conforms with design intentions of a designer.
The above-mentioned object may be achieved by rotating a
three-dimensional image for display by an angle predetermined with
respect to a relative positional relationship, based on the
relative positional relationship between the three-dimensional
image displayed on an image screen and an optional position on the
image screen which is designated by an operator.
The above-mentioned object may also be achieved by displaying an
image which is obtained by rotating the three-dimensional image by
90 degrees around a line orthogonal to a line connecting a center
position of a three-dimensional image displayed on an image screen
with an optional position on the image screen which is designated
by an operator.
The above-mentioned object may also be achieved, when an operator
designates one of a plurality of lines which compose a
three-dimensional image displayed on an image screen and a region
on the image screen partitioned by the line, by displaying an image
obtained by rotating the above-mentioned three-dimensional image by
an angle predetermined toward the region side around a line related
to the designation o a tangential line with respect to the
line.
The above-mentioned object may also be achieved, when a cutting
plane line and a visual point on an image screen are designated
with respect to a three-dimensional image displayed on the image
screen, by displaying a sectional view of the three-dimensional
image when the cutting plane line side is seen from the viewing
point.
The above-mentioned object may be achieved, when an operator
designates an optional point on an image screen with respect to a
three-dimensional image displayed on the image screen, by
displaying a perspective view of the three-dimensional image with a
line connecting the center of the three-dimensional image with the
above-mentioned point as the perspective direction.
The above-mentioned object may also be achieved, when a front view
of a three-dimensional image is displayed on an image screen, by
displaying a right side view of the three-dimensional image when an
operator designates the right side of the three-dimensional image
on the image screen, by displaying a left side view of the
three-dimensional image when the operator designates the left side
of the three-dimensional image on the image screen, by displaying a
top view of the three-dimensional image when the operator
designates the upper side of the three-dimensional image on the
image screen, and by displaying a bottom view of the
three-dimensional image when the operator designates the lower side
of the three-dimensional image on the image screen.
According to the present invention, a perspective view of the image
to be displayed next is determined from a relative position of the
designated point with respect to a design object which has been
already displayed by designating optional points and so forth on an
image screen by an operator. Therefore, the present system is
convenient to use, and an operating method conforming to original
design intentions of a designer is obtained.
Other objects and other features of the present invention will be
apparent from the description of embodiments stated hereunder.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory view for explaining a method of drawing up
a right side view according to a first embodiment of the present
invention;
FIG. 2 is an explanatory view for explaining a method of drawing up
a top view according to a first embodiment of the present
invention;
FIG. 3 is an explanatory view for determining a display direction
of a new view;
FIG. 4 is a block diagram of an image display system;
FIG. 5 and FIG. 6 are explanatory views for explaining the view
display in the image display system shown in FIG. 4;
FIG. 7 is a flow chart showing view drawing-up procedures in the
first embodiment;
FIG. 8 shows the relationship between a world coordinate system and
a view coordinate system;
FIG. 9 to FIG. 12 are explanatory views for explaining a view
drawing-up method according to a second embodiment of the present
invention;
FIG. 13 is a flow chart showing view drawing-up procedures in the
second embodiment;
FIG. 14 is an explanatory view for explaining a method of drawing
up a perspective view according to a third embodiment of the
present invention;
FIG. 15 is an explanatory view for explaining a method of drawing
up a sectional view according to a fourth embodiment of the present
invention;
FIG. 16 is an explanatory view for explaining a method of drawing
up a sectional view when a kinked line is adopted as a cutting
plane line; and
FIGS. 17A, 17B, 17C and 17D are explanatory views for explaining
designation of display directions in a conventional method.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be described hereafter in
conjunction with the accompanying drawings.
FIG. 4 is a block diagram of an image display system according to
an embodiment of the present invention. This image display system
includes an input unit 101 such as a keyboard or a pointing device
e.g. a mouse, an arithmetic and logic unit 102 which executes an
arithmetic or logical processing in accordance with a predetermined
program, a storage unit 103 for storing data and an output unit 104
such as a CRT and a LCD. Commands for operating the image display
system, configuring data of a design object and the like are input
from the input unit 101, and the arithmetic and logic unit 102
obtains a display perspective by analyzing input operation commands
and obtains shape or configuration data for display by executing
geometric computation of configuration data and so forth. Variety
of configuration data defined in the world coordinate system are
stored in advance in the storage unit 103, and the arithmetic and
logic unit 102 reads these configuration data and executes
geometric computation on the world coordinate system according to
necessity, to thereby convert the configuration data for display
thus obtained into a display coordinate system so as to determine
the display configuration, and displays those data on a CRT 104 as
a three-dimensional image.
FIG. 5 shows an example of a display image having a
three-dimensional configuration as in the image display system
shown in FIG. 4. There is a view 301 in which one three-dimensional
configuration of an object is seen from the front and a view 302 in
which the configuration is seen obliquely from above. The display
perspective and the display contents of respective views 301 and
302 have no relation to the display positions of the views in
general. Accordingly, even if the display positions of respective
views 301 and 302 are placed at positions shown in FIG. 6, the
display direction and the display contents in respective views 301
and 302 do not change at all.
Now, it is assumed that it is desired to display a right side view
of a three-dimensional configuration the front view of which is
shown in the view 301. In the present embodiment, when an operator
designates an optional position on an image screen, a relative
positional relationship of this designated position with respect to
the view 301 is obtained by the arithmetic and logic unit 102, thus
determining which of a right side view, a left side view, a top
view and a bottom view is desired by the operator. Since the
operator desires the right side view of the view 301 in this case,
the view 301 is designated first in order to show that the view 301
is the object to be optioned, and then an optional point in the
right side region of the view 301 is designated. For example, when
it is desired to designate the size of the right side view at the
same time, a left upper corner point 511 and a right lower corner
point 512 of a view 503 which is to be displayed newly are
designated as shown in FIG. 1. With this, the arithmetic and logic
unit 102 obtains configuration data of the objective right side
view by geometric computation and the like, from configuration data
in the world coordinate system, to display them. The position of
the optional point may be substituted by the center of the new
perspective view to thereby eliminate inputting of the optional
point. Description of such a case follows.
FIG. 2 shows an example showing a top view of a three-dimensional
configuration. In this case, the view 301 is designated first, and
then a position 611 and a position 612 are designated in a similar
manner as above, to thereby display a perspective 604 of the top
view.
FIG. 3 is an explanatory view when a display direction of a newly
formed perspective view is determined by the arithmetic and logic
unit 102. A view is given by dividing the image screen at intervals
of 45 degrees into regions 711 thru 718 with the center of an
objective view (the view 301 in the example shown in FIG. 1) as O.
Then, when the center position (the center between the left upper
corner point and the right lower corner point) of the new view
falls within the region 711 or the region 718, a view which is seen
from the right side relatively is formed, and when the center
position of the new view falls within the region 712 or the region
713, a view which is seen from above relatively is formed. Further,
when the center position of the new view falls within the region
714 or the region 715, a view which is seen from the left side
relatively is formed, and when the center position falls within the
region 716 or the region 717, a view which is seen from the lower
side relatively is formed. Such determination of the display
direction is in accordance with a third angle projection method of
drafting regulations, and the directions spear to be which is
familiar to a designer. Incidentally, a case in which the image
screen is divided into four equal parts has been described with
reference to FIG. 3, but the present invention is not limited
thereto. For example, display directions such as an obliquely right
upward direction or an obliquely left downward direction may be
designated by increasing the number of divisions. It may also be
arranged so that a line connecting a center position of a new view
with a center position of an objective view is adopted as a display
direction instead of dividing an image screen, and a new view which
is obtained by rotating the view by a predetermined angle, e.g., 90
degrees, around a line orthogonal to the above-mentioned line is
formed.
In the embodiment described above a region displayed with a
rectangle is called a view and the center position is adopted as a
reference, but the center of the view and the center of a shape or
configuration displayed in the view are different from each other.
Thus, computation and display are made so that, for example, the
mean value of the maximum coordinate value and the minimum
coordinate value of configuration data defined in the world
coordinate system is coincident with the center position of the
view. Besides, any method of computing the center position of a
displayed configuration may be employed. For example, a position of
the origin of the world coordinate system may be adopted as the
center position of the view.
Next, processing procedures of the arithmetic and logic unit
wherein the display direction is determined by dividing the image
screen into four regions as explained with reference to FIG. 3 will
be described in accordance with a flow chart shown in FIG. 7.
First, an input of a coordinate point P.sub.0 showing a reference
(objective) view is received (step 1). The coordinate values of the
point P.sub.0 are expressed with a coordinate system having
directions X toward the right on the image screen, Y toward the
upside of the screen and Z pointing "out" of the screen. Since it
is impossible to indicate a value in a direction perpendicular to
the image screen with an input by a general pointing device such as
a mouse or a tablet, the Z value is determined to "0".
Next, a view including the above-mentioned point P.sub.0 in a view
is retrieved among those views which are displayed on the image
screen, and is named as a view V.sub.0. When a plurality of views
are displayed being overlapped with one another and the point
P.sub.0 is located in the overlapped portion, an uppermost view in
which a configuration is displayed practically is adopted as the
view V.sub.0 (step 2).
When a reference view is specified to be the view V.sub.0,
information in the display direction of the three-dimensional
configuration displayed by the view among the information of the
view V.sub.0 is taken out of the storage unit (step 3). There are a
variety of display methods for the display direction of the view
V.sub.0, but the display direction is expressed with an origin and
directions of axis of coordinates of the view coordinate system on
the world coordinate system. For example, as shown in FIG. 8, such
an information that the view displayed on the screen has the center
O, and a right direction of a view (the right direction of the
screen is the same) displayed on the screen is the X-axis
direction, an upward direction of the view (the upward direction of
the screen is the same) is the Y-axis direction, and "outward"
direction of the view (this side direction of the screen is the
same) is the Z-axis direction becomes the information for the
display direction. Thus, in the image display system of the present
embodiment, a center coordinate of the view coordinate system, a
vector in the right direction, a vector in the upward direction and
a vector in this "outward" direction in the world coordinate system
are taken out in the step 3.
In a next step 4, inputs of diagonal points P.sub.1 and P.sub.2
which express a position and a size of a newly formed view are
received. These two points P.sub.1 and P.sub.2 are also expressed
with the coordinate system on the screen. When these two points
P.sub.1 and P.sub.2 are input, a middle point P.sub.12 thereof is
computed in a next step 5. This middle point P.sub.12 becomes a
point which corresponds to the center of the newly formed view,
which is adopted as a center position P.sub.00 of the reference
view V.sub.0 (step 6).
Next, the display direction of a configuration displayed in the
newly formed view is determined from the relative positional
relationship between the center position P.sub.12 of the newly
formed view and the center position P.sub.00 of the reference view
V.sub.0. First, it is judged whether the point P.sub.12 is located
on the right side of the point P.sub.00 or not (step 7). When it is
located on the right side, processing is advanced to a step 8, and
an OX'Y'Z' coordinate system which has been obtained by rotating
the OXYZ coordinate system by 90 degrees around the Y-axis is
computed. As a result, the origin O and the Y-axis direction are
not changed, the Z-axis direction takes the original X-axis
direction, and the X-axis direction takes a direction opposite to
that of the original Z-axis. Accordingly, the three-dimensional
configuration displayed in the new view shows a shape in which the
configuration displayed in the reference view V.sub.0 is seen from
the right side.
In case the judgement in the step 7 shows a negative result,
processing is advanced to a next step 9, and it is judged whether
the point P.sub.12 is located on the upper side of the point
P.sub.00 nor not. When it is located on the upper side, processing
is advanced to a step 10, and the OX'Y'Z' coordinate system
obtained by rotating the OXYZ coordinate system by -90 degrees
around the X-axis is computed. As a result, the three-dimensional
configuration displayed in the new view shows a shape in which the
configuration displayed in the reference view V.sub.0 is seen from
above.
In case the judgement in the step 9 shows a negative result,
processing is advanced to a next step 11, and it is judged whether
the point P.sub.12 is located on the left side of the point
P.sub.00 or not. When it is located on the left side, processing is
advanced to a step 12, and the OX'Y'Z' coordinate system obtained
by rotating the OXYZ coordinate system by -90 degrees around the
Y-axis is computed. As a result, the three-dimensional
configuration displayed in the new view shows a shape in which the
configuration displayed in the reference view V.sub.0 is seen from
the left side.
In case the judgement in the step 11 shows a negative result, in
other words, when the point P.sub.12 is located on the lower side
of the point P.sub.00, processing is advanced from the step 11 to a
step 13, and the OX'Y'Z' coordinate system obtained by rotating the
OXYZ coordinate system by 90 degrees around the X-axis is computed.
As a result, the three-dimensional configuration displayed in the
new view shows a shape in which the configuration shown in the
reference view V.sub.0 is seen from below.
After the steps 8, 10, 12 and 13, processing is advanced to a step
14, and a new view V.sub.1 is formed practically and the position
and the size on the image screen are set to the new view V.sub.1 in
the form of diagonal points P.sub.1 and P.sub.2 (step 15). In a
next step 16, the display direction is set in the form of the
OX'Y'Z' coordinate system, and the new view V.sub.1 is finally
displayed (step 17).
Incidentally, it has been described that the configuration of a
view is a rectangle in the above-mentioned embodiment, but the
present invention is not limited to the configuration of the view,
and either a circle or a triangle or an optional configuration
designated by a user may be employed. In case of an optional
configuration, the center of the view is positioned at a
geometrical center of gravity or at a center position of the top
and bottom ends and the right and left ends. Furthermore, display
directions of a new view have been described to be four directions,
right above, right side, left side and right under. However, in
case other drafting regulations are applied, other directions may
be adopted as described previously.
Next, another embodiment of the present invention will be
described. It happens sometimes that a design engineer desires to
display a configuration which is seen from a perpendicular
direction with respect to one straight line 811 which composes the
configuration displayed in the existing view 301 as a view 805 as
shown in FIG. 9. This view 805 is a perspective view which can be
seen when the configuration displayed in the view 301 is rotated by
90 degrees around the straight line 811. In the present embodiment,
this straight line 811 is designated, and then points 812 and 813
showing the display position and the size of the new view 805 are
designated, thereby to display the view 805. In a conventional
case, a rotating direction has to be designated with numeric
values, etc. in addition to designating the straight line 811,
which has been troublesome. In the present embodiment, however, a
view which has been rotated is obtainable only by designating the
points 812 and 813. That is, the rotating direction is determined
depending on the side of the region where the center position of
the new view is located with the straight line 811 (a straight line
911 extended therefrom) as the border. When the center position of
the new view is located in the region on the upper side with
respect to the straight line 811, a configuration which is seen
from above perpendicularly with respect to the straight line 811 is
displayed as the view 805, and, when the center position of the new
view is located in the region on the lower side, a configuration
which is seen from below perpendicularly with respect to the
straight line 811 is displayed as a view 906. Since this display
direction is also a direction based upon drafting regulations, this
is a method of determining the direction which is familiar to a
designer. Naturally, it is also possible to judge the rotating
direction from the relative positional relationship of respective
center positions of an existing view and a new view.
The straight line 811 shown in FIG. 9 is a line parallel to the
image screen, but it is an oblique line sometimes as a line on a
practical three-dimensional configuration. In such a case, an
unexpected configuration is displayed if the line is adopted as the
axis of rotation. Therefore, when a view 1002 seen from a direction
perpendicular to a straight line 1011 of a reference view 1001 is
formed, as shown in FIG. 11 for instance, display is made in a
direction rotated by 90 degrees around a straight line 1012
obtained by projecting the straight line 1011 onto a plane parallel
to the view 1001. Because the straight line 1011 is the straight
line 1011 shown in the view 1002 three-dimensionally, and is not
parallel to the image screen in the view 1001.
Next, view forming procedures described above will be explained in
accordance with a flow chart shown in FIG. 13 while referring to
FIG. 12.
First, an input of a coordinate point P.sub.0 is received (step
21). Next, a reference view V.sub.0 containing the point P.sub.0 is
retrieved (step 22). Then, when the reference view V.sub.0 is
specified, information of the reference view V.sub.0 is taken out
(step 23). Up to this step, processing is the same as the steps 1
to 3 shown in the flow chart in FIG. 7. Here, the difference exists
in that an operator inputs the point P.sub.0 as pointing a straight
line which becomes an axis of rotation in the reference view.
In a next step 24, a line segment L.sub.0 which is closest to the
point P.sub.0 among straight lines composing a configuration
displayed in the reference view V.sub.0 is retrieved. Then,
coordinates P.sub.01 and P.sub.02 are computed when coordinate
positions of both end points of the line segment L.sub.0 are
projected on the screen of the reference view V.sub.0 (step 25).
Then, the difference in a depth direction on the screen (namely, in
the direction of the OZ axis in FIG. 8) is disregarded. In other
words, the straight line 1012 obtained by projecting the line 1011
on the image screen is obtained instead of the line 1011 shown in
FIG. 11.
Next, inputs of diagonal points P.sub.1 and P.sub.2 which show the
position and the size of a view V.sub.1 to be newly formed are
received (step 26). Then a middle point P.sub.12 between the points
P.sub.1 and P.sub.2 is computed (step 27). These steps are same as
the steps 4 and 5 shown in FIG. 7.
In order to judge the direction for rotating a configuration to be
displayed in a new view V.sub.1 with respect to the configuration
displayed in the reference view V.sub.0, it is necessary to know on
which side of the straight line L.sub.0 the middle point P.sub.12
is located. Thus, a factor k used for such judgement is computed
first (step 28). This computation method will be explained with
reference to FIG. 12.
Two vectors are considered in the coordinate system on the image
screen shown in FIG. 12. A first vector is a vector which starts
from an end point P.sub.01 of the line segment L.sub.0 for a center
point P.sub.12 of a new view V.sub.1, and a second vector is a
vector which starts from the end point P.sub.01 for an end point
P.sub.02. When a vector product of the first vector and the second
vector is computed, a vector product which is perpendicular to both
the first and second vectors is obtained. When it is assumed that
the line segment 811 is the designated line L.sub.0 in FIG. 10,
this vector product appears as a vector toward the "outward" side
of the image when the new view is located at a position of a view
805, and appears as a vector toward the depth direction in the
image when the new view is located at a position of a view 906.
Here, a third component of this vector product vector, viz., the
component in Z-axis direction is adopted as the factor k.
In a step 29 shown in FIG. 13, it is judged whether the value of
this factor k is smaller than "0" or not. When the result of
judgement is positive, that is, when k<0 is satisfied,
processing is advanced to a step 30, and an OX'Y'Z' coordinate
system obtained by rotating a view coordinate system (OXYZ
coordinate system) in the world coordinate system by -90 degrees
around the axis L.sub.0 is computed. With this, the view 906 is
obtained in the example shown in FIG. 11.
When the result of the judgement in step 29 is negative, that is,
when it shows k>0, processing is advanced to a step 31, and an
OX'Y'Z' coordinate system obtained by rotating the view coordinate
system (OXYZ coordinate system) in the world coordinate system by
+90 degrees around the axis L.sub.0 is computed. With this, the
view 805 is obtained in the example shown in FIG. 11.
Steps 32, 33, 34 and 35 thereafter are the same as in the steps 14
to 17 shown in FIG. 7.
In the present embodiment, one of the straight lines composing a
configuration displayed in the reference view has been adopted as a
straight line used for the axis of rotation. However, the present
invention is not limited to a straight line. Even when contour
lines of three-dimensional circles, cylindrical faces or conical
faces show a straight line in the display on the screen, it is
possible to adopt them as the axis of rotation. Furthermore, even
when the counter lines show a curve in the display on the screen,
it is also possible to adopt the tangential line thereof as the
axis of rotation.
Next, still another embodiment will be described with reference to
FIG. 14. In the present embodiment, a perspective view in which a
three-dimensional configuration displayed in a reference view is
seen from an optional direction is formed. When a view 1101 is a
reference view and it is desired to display an image in which this
three-dimensional configuration is seen from the direction of a
straight line 1111, the arithmetic and logic unit recognizes a
designated display direction by designating the straight line 1111
by means of a pointing device, and, when diagonal points 1112 and
1113 which show the display position and the size of a new view
1102 are inputted in the next place, a perspective view thereof is
displayed. The straight line 1111 may be formed either by newly
inputting two designated points or by utilizing a line which has
already been drawn in the reference view. In the example shown in
FIG. 14, a perspective view is obtained by designating the line
1111 drawn in the reference view with a mouse. When the straight
line 1111 is designated, there are two display directions, but it
is determined which direction is to be adopted from the relative
positional relationship between the designated position of the
straight line 1111 and the center of the view 1102. Here, the view
on the right side of the reference view 1101 shown in FIG. 14 is a
perspective view obtained by designating a center line in a
horizontal direction in the reference view.
When forming this perspective view, and in the case of the
embodiment explained with reference to FIG. 10, the position of the
configuration in the new view is not determined. Therefore, the
position of the configuration is determined, for example, such that
the center of a straight line viewing perpendicularly or a straight
line designating the viewing direction coincides with the center of
the new view.
Next, still another embodiment will be described with reference to
FIG. 15 and FIG. 16. The present embodiment relates to formation of
a sectional view of a three-dimensional configuration. A view 1601
in which a front view of a three-dimensional configuration is
displayed is adopted as the reference view, and one of lines drawn
therein is designated. For example, a center line 1603 in a
vertical direction is selected. Further, as shown in FIG. 15 for
instance, a display position of a new view 1602 is designated on
the right side of the view 1601. With this, the line 1603 is
adopted as a cutting plane line, and a sectional view in which this
section is seen from the right side is displayed in the new view
1602.
In an embodiment shown in FIG. 16, sectional views in case kinked
lines 1603 and 1704 are adopted as cutting plane lines are
displayed in new views 1702 and 1703. In the present embodiment, a
different view is formed for each straight line of cutting plane
lines. In case a kinked line composed of such a plurality of
straight lines is adopted as a cutting plane line, it is possible
to combine sections which are cut with simple planes by forming a
separate view for each straight line, thereby to form a composite
sectional view easily. In this case, since a plurality of views are
related to each other, it is a matter of course to provide means
which move respective views while keeping reference to each other
when the whole views are moved to a separate location on the image
plane. Besides, the kinked line is not limited to a combination of
two straight lines, and it is also possible to omit a sectional
view which is related to a part of the straight lines which compose
the kinked line. Furthermore, it is also possible to have the
cutting plane line include a curve such as a circular arc. In the
present embodiment, a composite sectional view is formed by
combining a plurality of views, however, it is needless to say that
all the sectional views may be displayed in one view.
According to the present invention, when configurations in which a
three-dimensional configuration such as a design object is seen
from various directions are displayed on an image plane, it is
possible to designate a display perspective by designating a
position on an image screen with a pointing device and the like,
thus obtaining an effect that the operation method is simple and
the way to use becomes easier.
Many different embodiments of the present invention may be
constructed without departing from the spirit and scope of the
invention. It should be understood that the present invention is
not limited to the specific embodiments described in this
specification. To the contrary, the present invention is intended
to cover various modifications and equivalent arrangements included
within the spirit and scope of the claims.
* * * * *